Ok, this does'nt have to happen. Not with the crabs either. The answer to the problem is water volume. If you're putting them into a pot just big enough to hold them, their bodies will cool down the water as they start to heat, and they suffer horribly.
The bigger the pot, the less suffering, because the animal cooks to death faster. A ten gallon pot at a rolling boil (lots of bubbles) will put a lobster into shock in about three seconds. Let the water reach a rolling boil before putting another one in. So if you get a nice huge pot, there's little suffering. Just make sure it's at a full on rolling boil, and you add them at a rate where it can stay at or near boiling. That's how us chef people do it.
As for steaming, at home, too cruel. I would'nt use anything less than a full commercial steamer. That's live steam under pressure in less than five seconds. Can't even imagine doing it at home and listening to them try to scuttle away.
